derevis

Hi All,

I’m quickly approaching 100K glorious miles on my 2013 Boxster 2.7L. I have no issues with car and absolutely love it.
However, my anxiety about Carbon build-up outside of the intake valves is also increasing. I understand this can be an issue with DFI engines, as the fuel is sprayed directly into the cylinder, and not across the valves where it normally washes away any carbon build up. I’ve seen some (non-Porsche) videos on YouTube that have me concerned.
It seems the most effective way to remove the build-up is by blasting the intakes with crushed walnut shells, but I’m not comfortable with the idea of performing this service myself yet.
Does anyone have any experience with this? I haven’t noticed any power loss, and she’s not throwing any codes. But I imagine this would be a long term, imperceptible kind of power loss. Should I be concerned, and add this to my list of maintenance items to look at soon? Is there any way to tell how bad it might without getting down into the intakes themselves? Or am I getting anxious for nothing?

Thanks in advance.


”...to keep it as new has been his dearest dream.”

Marine Blue

Honestly I haven’t seen anyone posting about this being an issue on any of the DFI Porsche’s as of yet and there are a bunch of 150k mile Boxster’s out there. More important at this point is to make sure your AOS is in good working order, make sure you’re not overfilling the oil and use premium fuels with cleaners to keep the injectors running clean.

KrisA

Porsche DFI engines seem to carbon up at around the same rate as other DFI only engines. I like this guy's 987.2 videos and he has a couple on carbon build up in the 9A1 engine:



It's probably a good idea to do these types of cleaning periodically.

Sir Ducer

I did mine at about 70k miles and it helped free up the engine a little.
Throttle response was a little less sharp when feathering the pedal from a pick up, but overall, it helped to reduce FC by about 0.2-0.5, not that it matters.

Key for me was to keep the car healthy. and for downtime and stuff done, it was worth it.

Landshark92

Oh lord, I just came from an N54 BMW and this is the last thing I wanted to hear. I cleaned them myself on that car and the carbon was BAD.

Paul Quilter

[QUOTE=derevis;17325899]Hi All,

I’m quickly approaching 100K glorious miles on my 2013 Boxster 2.7L. I have no issues with car and absolutely love it.
However, my anxiety about Carbon build-up outside of the intake valves is also increasing. I understand this can be an issue with DFI engines, as the fuel is sprayed directly into the cylinder, and not across the valves where it normally washes away any carbon build up. I’ve seen some (non-Porsche) videos on YouTube that have me concerned.
It seems the most effective way to remove the build-up is by blasting the intakes with crushed walnut shells, but I’m not comfortable with the idea of performing this service myself yet.
Does anyone have any experience with this? I haven’t noticed any power loss, and she’s not throwing any codes. But I imagine this would be a long term, imperceptible kind of power loss. Should I be concerned, and add this to my list of maintenance items to look at soon? Is there any way to tell how bad it might without getting down into the intakes themselves? Or am I getting anxious for nothing?

Thanks in advance.


Carbon only builds up excessively if the AOS valve fails and feeds oil into the intakes. I do not know of any issues due to DFI.

meteor10

Those are very informative videos, thanks for posting KrisA. My 13 Boxster S has about 35,000 miles on it, at what intervals should the AOS be changed?

Diamond Dave

Research on RXP additive , maybe snake serum , but Ive used it in my vehicles for the last 18 yrs. I like it for carbon build up.

Schwinn

Not trying to change your mind, but just to provide some data and my opinion on this stuff. First off, the website has lots of "big words" to make themselves sound smart. There is no reasonable explanation on the site from what I see, but a lot of marketing-ese. That scares me to begin with.

Looking deeper at the SDS, it seems to be 100% diesel fuel #2 from what I can see. So, basically, it's putting in some diesel fuel into the gasoline. I can't imagine that is helpful in any real way. There is no mention of any other chemicals or cleaners in the SDS...

I found a few links that test it (not the manufacturer's test data) and most places seem to say it doesn't work...

I wouldn't waste my time with that stuff, but to each their own... it probably won't hurt anything in these low quantities.

Kancamagus

Decarbonizing fuel additives mostly dont work in DI engines because the inside of the valves never see the fuel.

TMc993

In my experience, I've found that regardless of the make of automobile, using a high quality fuel, high quality oil of the correct spec, and performing maintenance as specified by the manufacturer, there is little to be gained by pouring any "additive" into the crankcase or fuel tank. The ingredients are often questionable and the cost of the stuff is ridiculous. Compare these additives from AutoZone to the cost of a gallon of gas:

Gumout Fuel System Treatment - 12 oz @ $6.49 = $69.22/gal
Chevron Techron Fuel System Cleaner - 32 oz @ $17.99 = $71.96/gal
Royal Purple Fuel Injector Cleaner - 6 oz @ $7.99 = $170.45/gal

Terry

derevis

Thanks a lot for those videos, KrisA. It doesn’t look too difficult, just time consuming. That’ll be a good bonding project for me, my son, and the car.
I noticed in the videos he didn’t mention advancing the motor so that the valves would be closed on the cylinder you’re cleaning, so none of that crap can fall into the cylinder. Am I wrong about this? Is there an easy way to do that?

CaymanCarver

All Top Tier gasoline contains detergents. I would only use extree additives in gas that was not Top Tier.
I run Mobil gas 91 octane Supremium+ in my Cayman and she LOVES that stuff. Supposed to be specially formulated for DFI engines.
Not sure about any effects on the backsides of the valves.

I searched on UTube for any vids on cleaning valves on the 9A1 engine but didn't see any.
Please post of any exist.

derevis

I went ahead and cleaned out my intake valves over the last couple of days and I'm glad I did. As I mentioned, I'm right at 100K miles and had no way of knowing whether my Air-Oil Separator (AOS) was working or not.
Based on the gentleman's video at 33K miles with a failed AOS posted above, I'd say mine is still working but I went ahead and replaced it anyway for $100.
It took about an hour for each cylinder, using a combination of a metal hook pick, rags with degreaser, and a toothbrush. The image of the paper towel is only one cylinder's worth of build up.
While I was in there I cleaned out all the runners, plenum, cleaned the load sensor with MAF sensor cleaner, and cleaned up the throttle body. After putting everything back together and firing her up, I immediately noticed an increase of ~50rpms up to ~650rpm, and a smoother idle.
After going down this road, I would say this is definitely a maintenance item that should be at least looked at no later than every 100K miles with these DFI engines and AOSs. It's not difficult to do, just a bit time consuming. Worth it in my opinion.
The above videos were excellent resources, as well as Mr. Richardson, . Especially towards the end where he explains how to re-install the engine cover, insulation, and carpet in the 981 Boxsters.

professsorz

I don't know of any reason to presume it wouldn't be a problem - it's simply the physics of combustion by-products. That's the number one reason I didn't look at 987.2s and later - I explicitly didn't want DFI. Also didn't want electric steering but that's a separate issue.